JPH053475A - Path retrieval system - Google Patents

Abstract

PURPOSE:To realize the path retrieval system in which a center or the like allows to retrieve plural bypass paths in parallel with respect to the path retrieval system in which plural bypass paths are retrieved in parallel when a fault takes place in a node or a link of a network. CONSTITUTION:When a fault takes place in a communication line 2 or a node 1 in the network provided with the node 1 and an arithmetic operation equipment 5 monitoring the state of the node 1 or the communication line 2, a center station 3 retrieves paths reaching a 3rd node IC closest to other end of the communication line 2 or the node 1 in which the fault takes place from a 1st node 1 closest to one end of the communication line 2 or the node 1 via 2nd nodes SP1-SPn adjacent to the 1st node 1S. Then a path retrieval section 300 which obtains a path shortest in terms of distance or time or whose transmission capacity is maximized is provided to an arithmetic operation equipment 5, and the path retrieval section 200 retrieves plural bypass in parallel to obtain a desired bypass.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network having a plurality of nodes connected by links, and an improved route search method for searching a plurality of detour routes in parallel when a failure occurs in a node or a link. It is about.

In recent years, in computer networks and the like, the influence of network failures has become more serious as the amount of data transmission increases. Therefore, in the event of a network failure, you can quickly find and set up a detour,
It is necessary to recover from the failure.

Therefore, there is a demand for a route search system capable of allocating a plurality of protection lines to be used for a bypass route in parallel at a center or the like.

[0004]

2. Description of the Related Art FIG. 6 is a network configuration diagram of a conventional example. In FIG. 6, reference numeral 1 is a node, which is connected to each other by a link 2. Node 1
A terminal device (not shown) is connected to the terminal if necessary. Further, 3 is a center station for collectively operating and managing the network, and each node 1 is connected to a control link 4 indicated by a dotted line in the figure.
Connected by.

With such a configuration, the center station 3 monitors the state of each node 1 or the link 2, and the optimum route is set based on the monitoring result. Now, when a failure occurs in the link 2 indicated by an X mark in the network shown in FIG. 6, an operation of allocating a protection line to be searched for and used as a bypass path until the failure is recovered is calculated in the center station 3. It was performed by the arithmetic unit 5 provided in 1. and the spare line was allocated.

[0006]

However, in the above-mentioned conventional route search method, the detour routes are searched one by one, and it is compatible with the failure recovery system in which a plurality of detour routes are searched in parallel. There wasn't. Therefore, there is a problem in that the failure recovery rate is reduced, and as a result, the recovery is costly.

Therefore, it is an object of the present invention to provide a route search system capable of allocating a plurality of protection lines used in a bypass route in parallel at a center or the like.

[0008]

The above problems can be solved by the structure of the apparatus shown in FIG. That is, in FIG. 1, (claim 1) a plurality of nodes are arranged on a network, and a node 1 forming a desired communication path by appropriately switching and connecting the communication lines 2 on this network, and the state of the node 1 or the communication line 2 In a network having a center station 3 equipped with an arithmetic unit 5 for monitoring
Is provided in the arithmetic unit 5 of the center station 3, and when a failure occurs in the communication line 2 or the node 1, from the first node 1S closest to one end of the communication line 2 or the node 1 in which the failure occurs, Optimal by searching for a route that reaches the third node 1C closest to the other end of the communication line 2 or node 1 in which a failure has occurred via the second nodes SP1 to SPn adjacent to the first node 1S. It is a route search unit that searches for various routes.

Then, the route search section 300 is configured to search for a plurality of detour routes in parallel to obtain a desired detour route. (Claim 2) In the network according to claim 1, the optimum route is selected such that the shortest distance is from the first node 1S to the third node 1C via the second nodes SP1 to SPn. To be configured.

(Claim 3) In the network of claim 1, the optimum route is selected by the first node 1S.
From the first node to the third node 1C via the second nodes SP1 to SPn.

(Claim 4) In the network of claim 1, an optimum route is selected by the first node 1S.
To the third node 1C via the second nodes SP1 to SPn, the transmission capacity is maximized.

[0012]

In FIG. 1, (claim 1) When a failure occurs in the communication line 2 or the node 1, the route search unit 300 provided in the arithmetic unit 5 of the center station 3
In the above, the node (first node) 1S closest to one end of the communication line 2 or node 1 in which the failure has occurred is the sender,
Also, the closest node (third node) 1C to the other end is determined as the chooser. Further, the data stored in the memory (not shown) of the center station 3 is read out and calculated to determine the nodes (second nodes) SP1 to SPn adjacent to the sender (first node) 1S as the search start points.

Then, a route from the sender (first node) 1S to the chooser (third node) 1C via the search start point (second node) SP1 is searched. From the sender (first node) 1S, the search start point (second node)
Also, the search for the route reaching the chooser (third node) 1C via the nodes SP2 to SPn.

Then, each search start point (second node) SP
At each node on the route passing through 1 to SPn, the optimum route is calculated, and a plurality of protection lines are assigned to obtain a desired detour route.

As a result, a plurality of protection lines to be used for the alternative route can be allocated in parallel in the center station 3. (Claim 2) The route searching unit 300 provided in the arithmetic unit 5 of the center station 3 is arranged to find the shortest route in terms of distance as the optimum route of the invention of Claim 1 described above.

That is, each search start point (second node) SP1
At each node on the route passing through SPn, the search starting point from which the distance is closest is calculated, and a plurality of protection lines are allocated to obtain a desired detour route.

As a result, it is possible to allocate a plurality of protection lines to be used for the alternative route in parallel in the center station 3. (Claim 3) The route searching unit 300 provided in the arithmetic unit 5 of the center station 3 is configured to obtain the shortest route in time as the optimum route of the invention of Claim 1 described above.

That is, each search start point (second node) SP1
At each node on the route passing through SPn, which search starting point is closest in time is calculated, and a plurality of protection lines are assigned to obtain a desired detour route.

As a result, a plurality of spare lines to be used on the alternative route can be allocated in parallel in the center station 3. (Claim 4) The route searching section 300 provided in the arithmetic unit 5 of the center station 3 seeks the route having the maximum transmission capacity as the optimum route of the invention of claim 1 described above.

That is, each search start point (second node) SP1
At each node on the route passing through SPn, the route from which search start point is the largest in capacity is calculated, and a plurality of protection lines are assigned to obtain a desired detour route.

As a result, it is possible to allocate a plurality of protection lines to be used on the alternative route in parallel in the center station 3.

[0022]

FIG. 2 is a network configuration diagram for explaining the operation of the embodiment of the present invention. FIG. 3 is a flow chart for explaining the operation of the embodiment of the second invention.

FIG. 4 is a flow chart for explaining the operation of the third embodiment of the invention. FIG. 5 is a flow chart for explaining the operation of the embodiment of the fourth invention. The same reference numerals denote the same objects throughout the drawings.

In FIG. 2, it is assumed that a failure has occurred in a link (not shown) connecting the nodes 1-5 and 1-6. In this case, the message (data) for recovering from the failure is broadcast (transmitted) from the node 1-5 to other nodes and the center station 3. Therefore, the node 1-5 that broadcasts this message is called the sender (Sender, S), and the node 1-6 that finally receives this message is the chooser (Ch
ooser, C). Computing device 5 in center station 3
Then, perform the operations described below.

First, (1) the information of the nodes 1-5 and 1-6 corresponding to the sender (S) and chooser (C) is obtained (see (1) in FIG. 3). (2) The nodes (search start points) 1-1 to 1-4 (referred to as SP1 to SP4) adjacent to the sender (S) shown in FIG. Confirm with (see (2) in Fig. 3).

(3) Each search start point (SP) from the sender (S)
1 to SP4) to search a route to reach the chooser (C) (see (3) in FIG. 3). (4) At each node 1 on the route passing through each search start point (SP1 to SP4), which search start point is closest in distance is calculated (see (4) in FIG. 3).

(5) Select the search starting point (i) (in this case, S
P1 to SP4 and i = 1 to 4). (See (5) in Figure 3). (6) It is checked whether each node on the searched route belongs to the route set first (see (6) in FIG. 3).

(7) When each node on the search route in the above (6) belongs to the route initially set, the search route currently under investigation is used (see (7) in FIG. 3).
. (8) In the above (6), when each node on the searched route is not a node belonging to the initially set route, this route is discarded (see (8) in FIG. 3).

(9) All search start points (SP1 to SP4)
Consider whether or not the survey was conducted (see (9) in Fig. 3). (10) When not all the search start points have been investigated in (9) above, repeat the operations after (5) above (see Fig. 3).
(See (10)).

(11) When all the search starting points are examined in (9) above, next, it is examined whether or not there is a route from the sender (S) to the chooser (C) (see FIG. 3). (See (11)).

(12) When there is no path in (11) above, the calculation is terminated (see (12) in FIG. 3). (13) When there is a route from the sender (S) to the chooser (C) in (11) above, it is examined whether or not the required number of routes (for example, 10 lines) can be secured (((3) in FIG. 3). See 13)).

(14) When the number of routes obtained in (13) above is secured, the calculation is terminated (see (14) in FIG. 3). (15) When the number of routes required in (13) above cannot be secured, the operations after (3) above are repeated again (see FIG. 3).
(15)). In this case, the number of routes required is, for example, 10
For example, it is assumed that the above-mentioned calculation up to (12) can secure a spare line of, for example, 5 lines. Then, in order to search and determine the remaining five backup circuits, the calculation from (3) above is repeated.

In this case, it is considered that the 5 reserved circuits that have already been reserved are in use, and the calculation is performed for the unused reserved circuits. That is, in the calculation of (4) in the flowchart shown in FIG. 3, the calculation result of which search start point at each node is closest in distance varies depending on the remaining amount of the protection line.

In this way, it is possible to determine the route and the protection line allocation when the shortest route length is used as the route search criterion. Next, the route search method using the shortest time route as the route search reference can be explained by a method similar to the above-mentioned method.

In this case, each search starting point (SP1
In each node 1 on the route passing through SP4), the node closest in time from the search start point is calculated instead of the node closest in distance from the search start point. In general, the time for switching connection of a line (link) at a node is longer than the time for a signal to propagate through a link, and therefore the arithmetic unit 5 of the center station 3 calculates the shortest route in time. This is shown in the flow chart in FIG. In the figure, the operation other than (4) 'is the same as the operation of the flowchart shown in FIG. 3, and therefore its explanation is omitted.

Further, the route search method using the maximum capacity route as the route search reference can be explained by a method similar to the above-mentioned method. Also in this case, the above (4)
In each node 1 on the route passing through each search starting point (SP1 to SP4), instead of calculating the node closest in distance from the search starting point by calculation, the route from the search starting point is capacity (line capacity) The maximum node is calculated. This is indicated by (4) ″ in FIG. The operation other than (4) ″ in the flowchart shown in FIG. 5 is the same as the operation in the flowchart shown in FIG.

[0037]

As described above, according to the present invention, a plurality of alternative routes can be searched in parallel.
It is possible to improve the recovery rate of failures.

[Brief description of drawings]

FIG. 1 is a principle diagram of the present invention,

FIG. 2 is a network configuration diagram for explaining the operation of the embodiment of the present invention,

FIG. 3 is a flow chart for explaining the operation of the embodiment of the second invention.

FIG. 4 is a flow chart for explaining the operation of the embodiment of the third invention,

FIG. 5 is a flow chart for explaining the operation of the embodiment of the fourth invention.

FIG. 6 is a network configuration diagram of a conventional example.

[Explanation of symbols]

300 indicates a route search unit.

Claims (4)

[Claims] 1. A node (1) which is arranged on a network and which forms a desired communication path by appropriately switching and connecting the communication lines (2) on the network, and the node (1) or the communication line ( Arithmetic unit that monitors the condition of 2)
In a network having a center station (3) having (5), when a failure occurs in the communication line (2) or node (1), the communication line (2) or node (1) in which the failure occurs
From the first node (1S) closest to one end of the node to the communication line (2) in which the failure has occurred via the second nodes (SP1 to SPn) adjacent to the first node (1S), or A route search unit (300) that searches for a route reaching the third node (1C) closest to the other end of the node (1) and finds an optimal route is provided to the center station (3).
The route search method is provided in the arithmetic unit (5), and the route search unit (300) searches for a plurality of detour routes in parallel to obtain a desired detour route. 2. In the network according to claim 1, the optimum route is selected from the first node (1S) to the third node (1C) via the second nodes (SP1 to SPn). A route search method characterized by making the distance to be the shortest. 3. The network according to claim 1, wherein the optimum route is selected from the first node (1S) to the third node (1C) via the second nodes (SP1 to SPn). A route search method characterized in that the time taken to do so is the shortest. 4. The network according to claim 1, wherein the optimum route is selected from the first node (1S) to the third node (1C) via the second nodes (SP1 to SPn). A route search method characterized by maximizing the transmission capacity of the route.